This application claims the priority of German Application No. 197 49 588.5, filed Nov. 10, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a method and a device for simulating an impression which is subjectively perceived by an occupant of a vehicle, in particular of a passenger car, when the vehicle is being operated.
U.S. Pat. No. 5,618,995 discloses a simulation unit which is provided for determining the stresses on a passenger in a vehicle, in particular an off-road motor vehicle. The simulation unit has a base plate which is fixedly attached to the ground or floor and on which, inter alia, a seat, a small foot plate and a steering wheel are mounted. The aforesaid components are mounted spatially and functionally separated from one another on the base plate. An oscillation exciter is arranged between each individual component and the base plate. The individual oscillation exciters which are assigned to the components can be actuated separately from one another and induce in the component corresponding, low-frequency oscillations, so-called "vibrations", which can be perceived through the human body. The values for oscillation excitation are extracted for this purpose from a data record which has been previously defined.
U.S. Pat. No. 5,434,783 A1 discloses a vehicle in which the background noise which can be heard within a passenger cell is influenced by sound waves. In addition to normal loudspeakers, use is also made here of a piezoelement which excites at least parts of the vehicle body to oscillate and thus influences it so as to emit soundwaves; i.e. the piezoelement acts like a coil of a loudspeaker, while the vehicle body represents the oscillating diaphragm. The previously known method and device make it possible to improve the subjective sensation within the passenger cell.
A more extensive design of the above development for influencing the subjectively perceived driving impression is known from German Patent document DE 195 31 402 A1. According to this publication, not only the air-borne sound but also the structure-borne sound or vibrations perceived through the human body are influenced as a function of a parameter and, in this context, in particular the engine speed and/or the vehicle travel speed. For this purpose, depending on the magnitude of the parameter, certain data are read out of a data field and, with the aid of oscillation exciters, converted into, inter alia, secondary oscillations which can be perceived through the human body as well. By means of these measures it is possible, in conjunction with the influencing of the acoustically perceived air-borne sound, to generate both positive and negative interference of the artificial secondary oscillations with the primary oscillations which are formed in the vehicle when the vehicle is being operated. The interference may, depending on what is desired, reduce the perceived impression or else simulate a specific impression, for example a gear-changing operation in a vehicle which is provided with an infinitely variable speed gearbox.
If a certain level of background noise gives rise to complaints with regard to a vehicle, it is difficult in some cases to find the corresponding fault. In particular, these difficulties are due to the fact that human language does not have unambiguous terms for specific noises. Furthermore, the absolute acoustic memory itself is limited, even in trained people, to a few minutes at most.
The object of the invention is to develop the basic method and device such the sources of complaints based on subjective sensations in a vehicle can be found.
This and other objects are achieved with a method for simulating a subjectively perceived impression by an occupant of a vehicle, in particular of a passenger car, when the vehicle is being operated. Primary oscillations which are produced when a vehicle which is to be investigated is being operated and which are perceived subjectively are registered. Data for generating secondary oscillations are acquired from the primary oscillations and converted into the secondary oscillations. The secondary oscillations are used to operate a simulation unit which simulates, inter alia, in particular a passenger car, at least representationally in certain areas. The simulation unit is elastically mounted or secured with respect to the floor on which it is positioned. The vibrations which can be perceived through the human body, called vibration oscillations, are extracted from the primary oscillations and converted into the vibration oscillations. The vibration oscillations are induced at at least one location of the simulation unit from which they are transmitted into a seat and/or into the steering wheel. An oscillation exciter which induces the vibration oscillations in the seat oscillates freely with respect to the simulation unit, i.e. the oscillation exciter is at most elastically positioned on the floor, preferably not at all, and specific frequencies of the vibration oscillations are changed selectively.
Also provided by the invention is a device for simulating an impression which is subjectively perceived by an occupant of a vehicle, in particular of a passenger car, when the vehicle is being operated. Oscillation exciters output secondary oscillations in a simulation unit, the secondary oscillations simulating operation of the vehicle and being acquired from primary oscillations which are produced when the vehicle is actually being operated. The body of the vehicle is elastically secured with respect to the ground on which it is positioned. One oscillation exciter which induces mechanical vibration oscillations which can be perceived through the human body in the seat is arranged in a freely oscillating fashion with respect to the seat and fixedly with respect to the vehicle body. The one oscillation exciter which induces the vibration oscillations in the seat is secured at most elastically, preferably not at all, with respect to the ground on which the vehicle body is positioned. Another oscillation exciter which induces mechanical vibration oscillations which can be perceived through the human body in the steering wheel is arranged in the region of the steering system. The seat and/or the steering wheel are able to be excited so as to undergo vibration oscillations which can be sensed through the human body.
By means of the method and device according to the invention it is possible to store, in particular in an electronic data carrier, the overall impression which is based on perceptions of an acoustic nature and also on the part of the human body while the motor vehicle is being operated. This impression can then be experienced again at any time in a reproducible fashion using appropriate equipment. An oscillation exciter which excites vibration oscillations is also advantageously assigned to the steering wheel. Here, it is, in particular, surprising that specific impressions cannot be re-experienced again at all unless corresponding vibration oscillations are also excited in the steering wheel. If, on the other hand, the steering wheel is not excited, a completely different impression is produced. By means of the selective influencing of specific frequencies, different influences can then be checked and, if appropriate, eliminated.
Advantageously, it is sufficient to use only the vehicle body with a completed or correspondingly simulated passenger compartment, instead of a completely mounted vehicle, for example. In order to localize a troublesome sound it is possible to manipulate individual frequencies, enabling the cause of the troublesome sound to be easily determined with the device. In particular, the so-called acoustic memory, i.e. the precise recollection of the impression acquired when the vehicle was actually being operated is prolonged by any desired degree. In addition, it is possible with this simulation unit to sense the influence of further developments subjectively and compare the further development with the previous art. Furthermore, new developments can also be appropriately investigated and compared.
The introduction of the vibration oscillations is carried out by means of freely oscillating, in particular electrodynamic, oscillation exciters and takes place on a vehicle body which is elastically mounted with respect to the ground--that is the floor on which the simulation unit is positioned. Because of the freely oscillating arrangement of the oscillation exciter, the latter is assigned to the vehicle body in a fixed manner and has at most an elastic support with respect to the ground, that is to say the floor, and preferably no support at all.
The generation of the vibration oscillations can be carried out in a manner analogous to the method known from the field of active noise reduction so that more details are not necessary here.
The amplification of specific frequencies or frequency patterns and/or in particular their suppression includes and relates to the vibrations which can be perceived by the human body and are noticed by the driver and/or the vehicle occupants. In this context, frequency pattern is understood to be a plurality of frequencies which have, for example, a specific envelope curve or, for example, even a specific fourier spectrum. The respective frequencies when the vehicle is being operated may originate, for example, from the engine, the chassis, the tires, the condition of the road or else from the activated windscreen wiper or fan.
For a simple embodiment of the invention, it may be sufficient for the subjectively perceived vibrations to have frequencies up to 150 Hz gated out of the air-borne sound signal, which can be registered by means of one or more microphones, for example, of the operated vehicle through the use of a low-pass filter. The vibration oscillations are generated with the gated-out low-frequency component. Using the signals which give rise to the vibration oscillations, oscillation exciters in particular are actuated. These exciters are arranged in the steering gear and/or on the seat rail. In particular, it is advantageous to use a modified signal additionally to drive a low-frequency loudspeaker which then covers the low-frequency component of the acoustic air-borne sound.
The method or the device according to the invention can also advantageously be used for sound design. This can be used, inter alia, for finding or designing a suitable location for a loudspeaker and also other components, for example.
In particular, in this way devices can be manufactured with which, for example, test runs with various vehicles can be simulated so that the customer can be provided with a comfortable system for helping him to make a decision. This is easily possible since during the simulated test runs it is necessary to use only specific data records which reproduce the impression which a vehicle occupant would perceive in a vehicle type which is used for the simulated test run. Here, the visually perceived impression can also additionally be simulated by video or other optical methods.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.